Automated means have been attempted for years to remove stoppers from test tubes or containers. Early approaches have been to "flip" out the stopper by leveraging one edge, as shown for example in U.S. Pat. No. 4,217,798 and German AUS No. 3,141,780. Such an approach creates the hazard of loose stoppers, or necessitates the use of a connector to secure unstoppered stoppers to their associated containers. To deal with this, more positive gripping means have been provided, for example devices using spikes that pierce the top of the stopper before pulling out the stopper, as shown in EPO No. 264,456. However, such piercing devices severly penetrate the stopper, and are not likely to be useful on stoppers or plugs made from relatively tough materials, e.g., plastic materials. Furthermore, the severe penetration of the stopper means that only a forceful withdrawal of the spikes will remove them from engagement with the stopper, as is necessary when restoppering the container. Such a forceful withdrawal requires pusher means of some kind, so that a simple reversal of part positions, e.g., the pulling apart of jaws on which the spikes are mounted, is apt to still leave the stopper impaled on one or more of the spikes.
Thus, there has been a need prior to this invention for an automatic stopper remover that positively engages the stopper to be removed, to keep from having loose stoppers, while at the same time provide for ready withdrawal of engagement of the stopper such as by reversing the action of the stopper gripping means.